Compact display panel

ABSTRACT

A display panel includes a first plate having slots for receiving anode electrodes and a surface for supporting cathode electrodes for operation with said anode electrodes. A cover plate covers the electrode assembly, with gas-filled spaces being provided, above each cathode, in which cathode glow can be generated facing a viewer. The anode electrodes are hidden from view and do not obstruct the cathode glow. The slots can also be used to provide communication of excited particles between adjacent anodes to facilitate the firing of adjacent cells.

United States Patent Inventor Appl. No.

Filed Patented Assignee James A. Ogle Paoli, Pa.

Dec. 1, 1969 Dec. 28, 1971 Burroughs Corporation Detroit, Mich.

COMPACT DISPLAY PANEL 20 Claims, 18 Drawing Figs.

3l3/l 09.5, 313/210, 315/169 R Int. Cl HOIj 17/16 Field of Search315/169 R, 169 TV; 313/220 [5 6] References Cited UNITED STATES PATENTS2,925,530 2/1960 Engelbart Primary Examiner-Raymond F. HossfeldAttorneys-Kenneth L. Miller and Robert A. Green ABSTRACT: A displaypanel includes a first plate having slots for receiving anode electrodesand a surface for supporting cathode electrodes for operation with saidanode electrodes. A cover plate covers the electrode assembly, withgas-filled spaces being provided, above each cathode, in which cathodeglow can be generated facing a viewer. The anode electrodes are hiddenfrom view and do not obstruct the cathode glow. The slots can also beused to provide communication of excited particles between adjacentanodes to facilitate the firing of adjacent cells.

PATENTED UEB28197I 3 531,530

sum 1 OF 6 V\ x f 72 x 250 2619 H62 (30 $0 64 i INVENTOR JAMES A. 06 L EMam ATTORNEY H0 37) u H INVESTOR, JAMES A. OGLE ATTORNEY PATENTEUM82819?! H7 FIG. l3 H7 200 10 520 go 12 0,113 :20 I y 1 j 7o INVENTOR.JAMES A. OGLE ATTORNEY PATENTEU 05628871 "3,631; 530

sum 5 or a INVENTOR. JAMES A. OGLE wfii 24244 AT TOR N EY COMPACTDISPLAY PANEL BACKGROUND OF THE INVENTION Various types of displaypanels comprising a plurality of gas-filled cells which can be turned onselectively to display a message are known in the art. In a recentdevelopment of H012 and Ogle, a display panel has been devised which hastwo layers of cells, a first layer being used as a scanning oraddressing layer for sequentially addressing the cells, and a secondlayer in which information is inserted to be displayed, and perhapsstored, as the first layer is scanned. These multilayer devices havebeen constructed of at least four layers of glass or other insulatingmaterial with electrodes suitably positioned between them, at least twoof the layers containing a matrix of closely spaced apertures whichserve as gas cells. Although these devices have been built and operatedsuccessfully, there is a need to provide economies by eliminatingcomponent parts, such as one or both of the apertured glass plates. Thepresent invention provides such economies and achieves the effect offour layers or plates with but two plates.

SUMMARY OF THE INVENTION Briefly, a display panel embodying theinvention includes an arrangement of plates and cathode glow electrodesand anode electrodes such that cathode surfaces are available to glowand face the viewer with no obstruction to viewing therebetween. Thepanel also includes favorably disposed drift spaces for excitedparticles to flow from scanning cells to display cells in one mode ofoperation.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a displaypanel embodying the invention;

FIG. 2 is a sectional view along the lines 2-2 in FIG. 1;

FIG. 3 is a sectional view along the lines 3-3 in FIG. 1;

FIG. 4 is a sectional view along the lines 4-4 in FIG. 1;

FIG. 5 is a sectional view along the lines 5-5 in FIG. 1;

FIG. 6 is perspective view of a portion of the bottom surface of ourcover plate of the panel of FIG. 1 and portions of associatedelectrodes, the view illustrating one form of a portion of the panel;

FIG. 7 is a view similar to that of FIG. 6 showing a modification of aportion of the panel;

FIG. 8 is a sectional, elevational view of a portion of a panel showinganother modification of a portion of the panel of FIG.

FIG. 9 is a perspective view of a portion of a panel showing anothermodification of the invention;

FIG. 10 is a perspective view of a portion of a panel showing anothermodification;

FIG. 11 is a sectional, elevational view of a panel showing anothermodification of the invention;

FIG. 12 is a plan view of a portion of the panel of FIG. 11;'

FIG. 13 is a plan view of a panel showing a modification of a portion ofthe invention; and

FIG. 14 is a sectional elevational view of another modification of theinvention.

FIG. 15 is a sectional elevational view of a modification of a portionof the invention;

FIG. 16 is a perspective view of another modification of a portion ofthe invention;

FIG. 17 is a sectional view, along the lines l717, in FIG. 16; and

FIG. 18 is a sectional view, along the lines l818, in FIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The display panel shown in thedrawings and described below includes relatively few display cells;however, it is to be understood that the panel may be made in almost anysize and with almost any number of display cells.

Display panel 10 embodying the invention includes a lower plate 20 ofglass, ceramic, or the like, and preferably opaque to prevent lightcrosstalk, having a top surface 30 and a bottom surface 40. Plate 20 isprovided with a plurality of first parallel slots 50 which alternatewith second parallel slots 56, the slots being shown as having arectangular cross section, but they may have any suitable cross section,and they may or may not be identical in shape and size. The slots 50 and56 extend a suitable distance from the top surface 30 toward the bottomsurface 40 of plate 20. In panel 10 and for purposes of laterdescription of one mode of operation, slots 50 are defined as displayslots, and slots 56 are defined as counting slots.

An electrode 60, operable as a display anode, is disposed in each slot50, and an electrode 66, operable as a counting or scanning anode, isdisposed in each slot 56. Electrodes 60 and 66 may be separate wires,flat strips, or the like, which are set into their slots, or they may befilms or coatings plated or evaporated into their slots. The electrodes60 and 66, if they are separate wires or strips, may also be secured inplace by means of a cement such as a glass frit or the like (not shown)placed at the ends of the electrodes and their slots or at any suitablelocation. The electrodes may also be held in place by the seal betweenthe various parts of the panel (to be described).

A plurality of electrodes 70, operable as cathode electrodes andpreferably in the form of flat strips having top surfaces 71 and bottomsurfaces 72, are disposed on the top surface 30 of plate 20 andoriented, preferably, at a angle to the parallel anode electrodes 60 and66. Each cathode electrode 70 crosses each of the anode electrodes, andeach such crossing defines a gas cell, with the cells associated withthe display anodes being display cells 74, and those associated with thecounting or scanning anodes being counting or scanning cells 76. Cells76 are also known as priming cells since, in one mode of operation, theyprovide excited particles which prime and facilitate the firing ofdisplay cells 74.

The panel 10 is completed by a cover or viewing plate 80, which has atop surface 90 and a bottom surface 100, (FIGS. 1 and 2) which is sealedgastight to the bottom plate 20 by means of a suitable cement such as aglass frit or the like 102 secured to the edges of the top and bottomplates.

According to the invention, the top plate 80 and/or the associatedelectrodes 70 are constructed so that gas-filled viewing spaces orviewing cells 110 are provided above selected portions of the topsurfaces 71 of each of the cathode electrodes 70. These spaces may beprovided by means of parallel slots or depressions 112 which are formedin the bottom surface of the top plate and extend along the lengththereof transverse to the cathodes 70 (FIGS. 1 to 6). The desiredarrangement may also be provided by fusing strips of glass frit or thelike 114 to the bottom surface of the top plate so that the depressions112 are provided between them, as shown in FIG. 7.

Since the cover plate 80 rests on the cathodes 70, spaces 120 areprovided between the bottom surface of cover plate 80 and the topsurface of baseplate 20. Preferably, all of these striplike portions ofthe bottom surface 100 (thus, in effect, all of the bottom surface ofplate 80) are blackened to render them opaque. In FIG. 7, the glass fritstrips 114 are made with a black glass frit which can be purchasedcommercially. The black areas in the other FIGS. can be made of a thinfilm of a black glass frit or with any suitable inorganic substancewhich will not interfere with the operation of the panel and its gas.

The spaces or display cells can also be provided by properly shaping thecathode strips 70. For example, as shown in FIG. 8, if the cathodes haveraised areas 116 spaced apart along their lengths, this has the effectof providing spaces 1 10 between the bottom surface of the top plate 80and the portions 117 of the cathodes between the elevations 1 16.

For one mode of operation of panel 10, the spaces 110 which extend alongthe entire length of the panel, are provided for, and aligned with, eachdisplay anode 60, with the black areas of surface 106 being providedfor, and aligned with, each scanning anode 66. The spaces or displaycells 110 are of such width that each overlays its associated displayslot 50 with which it is aligned and extends into the space betweenadjacent slots 56. The display spaces 1 10 may extend up to the slots 56on either side of a display slot 50.

It can be seen that the black areas of surface I overlaying counting orscanning slots 56 prevent light generated therein from being seen by aviewer looking through the top or viewing plate 80.

The panel includes a suitable ionizable gas or mixture of gases selectedfrom the group consisting of argon, neon, xenon, krypton, etc., and asmall quantity of mercury is usually added to the gas to minimizecathode sputtering. The gas is introduced by means of a tubulation (notshown) secured to one of the plates or 80, or it is introduced in anyother suitable manner.

As noted above, each crossing of a cathode 70 and a counting node 66defines a counting cell 76, so that each cathode forms a column ofcounting cells. Thus, beginning at the left in PK}. 1, there arecathodes 70A, 70B, 70C, etc. depending on how many columns of cells areprovided. Similarly, each crossing of a cathode and a display anodedefines a column of display cells 74. In panel 10, each column of cellsincludes display cells 74 and counting cells 76 aligned in commoncolumns with display cells and counting cells alternating with eachother in a common column.

Panel 10 may be operated in difierent ways, some of which will bedescribed in different degrees of detail. In one mode of operation, thefirst cathode 70A, associated with the first column of cells, at theleft end of panel 10, is connected to ground or other generally negativepotential, and all of the counting anodes 66 are connected to a sourceof positive potential such that a firing potential appears across eachcounting cell 76 formed by these anodes and the first cathode 70A. Thefirst column of counting or scanning cells 76 now fires and glows;however, this glow is not visible through the black areas of surface 100of cover plate 80 which cover these cells. With cells 76 ON, excitedparticles generated thereby, particularly metastable atoms, flow out ofslots 56 through the spaces between adjacent cathodes 70 into theadjacent display slots 50 and into the spaces or display cells 110 abovethe cathodes 70.

If now, as the counting cells 76 in the first column are turned on,signal information, in the form of a positive voltage, is applied to oneor more of the display anodes 60, then the display cells 74 in the firstcolumn, which include these energized anodes, fire and glow. This firingoperation is facilitated by the priming action of the excited particlespresent in these cells. The glow thus generated in the cells 74 startsbelow the cathodes 70 and spreads to the top surface of the cathodes 70in the spaces or display cells 110 and is visible to a viewer.

If now, signals representing information to be displayed are applied tothe anodes 60 of the display cells 74 which have been turned on, thecurrent flow therethrough can be modulated to provide a correspondinglevel of intensity of glow in the cells 74. This modulation can beachieved by modulation of the current amplitude or by modulation of thepulse width of the applied information signal.

The above-described operation is repeated for the second column of cellsby the removal of turn on potential from the first cathode 70A and theapplication thereof to the second cathode 70B associated with the secondcolumn of counting or priming cells '76 and display cells 74. Selectedanodes again are energized as described above to turn on and provideproperly modulated glow in selected associated display cells 74. Thismode of operation is carried out cyclically, with each of the cathodesand the proper anodes being energized in turn and at such a rate that astationary but changeable message or character can displayed by thepanel and visible through plate 80.

In a modification of the invention shown in FIG. 9, each cathode strip70 is provided with slots 140 along its length, each of which extendsacross a display slot 50 and across the adjacent solid portion of plate20 to overlay a portion of the adjacent counting slot 56. Such slots 140facilitate communication between the counting cells 76 and the adjacentdisplay ls 74 by providing a more direct path for the flow of excitedarticles from an ON counting cell to a display cell to be turned on.Thus, for example, if the counting cells 76 associated with a cathode70A and anodes 66 are ON and exhibiting glow and a display anode 60Areceives an information signal, then, with excited particles present dueto flow from the adjacent cell through cathode slot 140A to theassociated display cell A, turn on ofcell 110A above cathode 70A isfacilitated.

If desired, the slots may be extended to the ends of the cathodes, asillustrated briefly in FIG. 10, so that each cathode is actually nowmade up of two narrower cathode strips 70.

In still another modification of the invention shown in FIGS. I1 and 12,the necessary communication paths comparable to slots 140 are providedas narrow elongated depressions 180 formed in the bottom surface of eachcathode and extending between counting slots 56 and display slots 50, asdesired. Communication might also be provided by means of slots out intothe top surface of plate 20, with or without cathode depressions 160.

In order to control the diffusion or spread of glow from counting cells,it may be necessary to set the cathodes, in FIGS. Ill and 12 or in anyof the other structures, into the bottom surface of cover plate 80 orinto the top surface of lower plate 20!.

As shown in FIG. R3, in any pertinent embodiment of the invention, thecathode slots 140 might extend between a counting slot 56 and bothadjacent display slots 50 so that one counting slot could operate withtwo adjacent display slots.

The display panel described herein may also be modified to utilize everyslot and every cathode portion associated with it as a display cell.Such a panel shown in FIG. 14 includes bottom plate 20 with identicalslots in which anode wires 220 are seated. The bottom plate thus may beidentical in construction to the same plate shown in FIG. 1. The cathodeelectrodes 70 are provided as above; however, the top plate is modifiedto provide display spaces 110 extending along and overlying each slot.In this type of panel, when operating potential is ap plied to eachanode and each cathode, cathode glow will originate at the bottomsurface of the energized cathode and will spread to the space 110 abovethe associated cathode portion 117.

In the modification of the invention shown in FIG. 15, the display cells110 are extended so that they are close to, or even slightly overlap,the counting slots 56. With this arrangement, the flow path for excitedparticles, from a counting cell to a display slot 50 and display cell110, is shortened.

In another modification of the invention shown in FIGS. 16 to lid, thetop surface of bottom plate 20 is provided with slots 212 (one shown)which lie under the cathode strips 70 and are concealed thereby. Thecathode strips are provided with small apertures 214 (one shown)disposed along their lengths and positioned between a lower countingslot 56 and a lower display slot 54) but beneath an upper display cell110. The aper' tures 214 are small enough so that glow from a countingcell in plate 20 cannot enter a display cell 110, but they are largeenough so that excited particles in the glow can prime a display celland prepare it for firing when firing potentials are applied.

In the various embodiments of the invention illustrated, the exact sizesand spacing of the various parts have not been shown with dimensionalexactness. Although the theory of operation of gas discharge devices maynot always be wellknown, and this is particularly true of new devices ofthe type described herein, presently known theory seems to suggest thatspacings of parts and dimensions of spaces between parts in the vicinityof counting cells formed in the lower plate of the devices should besuch that small quantities of excited particles can diffuse to thevicinity of adjacent display areas for priming purposes, but noconsiderable glow mass should be able to diffuse and spread from cathodeareas used for counting glow to cathode areas used for display. ingeneral, an aperture of l to 3 mils is the proper size to presentspurious spreading.

What is claimed is:

l. A display panel including a gas-filled envelope comprising a firstinsulating baseplate and a transparent cover plate,

said first plate having a top surface and a bottom surface and having aplurality of pmallel slots extending from said top surface downwardlytoward said bottom surface, first electrodes in one group of said slotsand second electrodes in another group of said slots with first andsecond electrodes alternating with each other in alternate slots,

said first electrodes being designated counting electrodes and saidsecond electrodes being designated display electrodes, and

a plurality of third electrodes disposed on said top surface of saidfirst plate and oriented perpendicular to said first and secondelectrodes,

each third electrode crossing a portion of each first and secondelectrode, each crossing of a third electrode and a first electrodedefining a counting cell, and each crossing of a third electrode and asecond electrode defining a display cell,

said cover plate being spaced from each portion of each third electrodewhich is associated with a display cell to provide a display space inwhich gas glow can be viewed through said cover plate,

there being a particle flow space extending from each counting cell toan adjacent display cell and to said display space associated therewith.

2. The panel defined in claim 1 and including opaque areas obstructingviewing of said counting cells through said cover plate.

3. The panel defined in claim 1 wherein said cover plate has a topsurface and a bottom surface, and opaque areas are pro vided on saidbottom surface of said cover plate to shield selected ones of said cellsfrom view through said cover plate.

4. The panel defined in claim 3 wherein said bottom surface of saidcover plate is provided with depressions which form said display spacesabove each said third electrode.

5. The panel defined in claim 3 wherein said bottom surface of saidcover plate has layers of insulating material secured to it to form eachsaid display space between them.

6. The panel defined in claim 3 wherein said first plate is of an opaqueinsulating material to minimize light crosstalk between said gas-filledcells when said cells glow.

7. A display panel including a gas-filled envelope consisting of a firstinsulating baseplate and a second insulating cover viewing plate,

means fonning a plurality of gas-filled cells in a common layer in saidenvelope, an anode electrode and a glow cathode electrode associatedwith each cell, the anode electrode being positioned within saidbaseplate and said cathode being positioned in contact with saidbaseplate adjacent to said cover plate,

each cathode being in operative relation with at least two of said cellsand with the anode electrodes therein, each such cathode including aslot providing gas communication between said two cells.

8. The panel defined in claim 7 and including means concealing at leastone of said cells from view so that, when said one cell glows, the glowcannot be seen but excited particles generated by the glow can flowthrough said slot in said cathode to the other cell to prime said othercell for subsequent firing.

9. The panel defined in claim 8 wherein said cover plate is in contactwith a portion of said cathode which overlays said one cell and isspaced from the portion of said cathode which overlays said other cell,the space provided thereby being a glow display space which presentsunobstructed display to a viewer looking through said cover plate.

10. A display panel including a gas-filled envelope comprising a firstinsulating baseplate and an insulating top cover viewing plate,

said first base plate having a top surface and a bottom surface withsaid top viewing plate sealed thereto in gastight engagement, said topplate having a top surface and a bottom surface, a plurality of parallelslots in said first plate, first electrodes seated in said slots remotefrom said top surface of said first plate, I

second electrodes seated on said top surface of said first plate andoriented parallel to each other but at an angle to said first electrodeswhereby each second electrode crosses each of said first electrodes andeach crossing forms a gas-filled cell including a portion of a firstelectrode and a portion of a second electrode as the electrodes for thecell,

said top plate being seated on portions of said second electrodes,

said top plate being spaced from other portions of said secondelectrodes whereby a gas-filled display space is provided between saidother portions of said second electrodes and said cover plate, therebeing a gas communication path extending from each said first electrodethrough its said slot and between adjacent second electrodes into anadjacent slot and into the said gas-filled space above the portion ofsaid second electrode associated with said adjacent slot.

11. The panel defined in claim 10 and including means obstructingviewing of selected ones of said cells through said top plate.

12. The panel defined in claim 10 and including opaque areas provided onsaid bottom surface of said top plate to shield selected ones of saidcells from view through said top plate.

13. The panel defined in claim 12 wherein said bottom surface of saidtop plate is provided with depressions which form said display spacesabove each said second electrode.

14. The panel defined in claim 12 wherein said bottom surface of saidtop plate has layers of insulating material secured to it to form eachsaid display space between them.

there being particle flow space extending from each counting cell to anadjacent display cell and to said display space associated therewith.

15. The panel defined in claim 1 and including means concealing saidcounting cells from view so that, when each said counting cell glows,the glow cannot be seen by a viewer but excited particles generated bythe glow can flow through said particle flow space to adjacent displaycells to prime said display cells for subsequent firing.

16. the panel defined in claim 1 wherein said third electrode includesslots which extend from a counting cell to an adjacent display cell.

17. The panel defined in claim 16 and including means concealing saidcounting cells from view so that, when a counting cell glows, the glowcannot be seen by a viewer but excited particles generated by the flowcan flow through one of said slots in said third electrode to anadjacent display cell to prime said display cell for subsequent firing.

18. The panel defined in claim 16 wherein said slots extend along theentire length of each third electrode so that in effect each thirdelectrode comprises two narrow spaced-apart electrode portions.

19. The panel defined in claim 1 wherein each third electrode has bottomsurface provided with depressions providing communication paths betweenadjacent first and second slots.

20. The panel defined in claim I wherein'said third electrodes includeapertures providing direct communication between selected ones of saidslots and the space above said third electrodes.

1. A display panel including a gas-filled envelope comprising a firstinsulating baseplate and a transparent cover plate, said first platehaving a top surface and a bottom surface and having a plurality ofparallel slots extending from said top surface downwardly toward saidbottom surface, first electrodes in one group of said slots and secondelectrodes in another group of said slots with first and secondelectrodes alternating with each other in alternate slots, said firstelectrodes being designated counting electrodes and said secondelectrodes being designated display electrodes, and a plurality of thirdelectrodes disposed on said top surface of said first plate and orientedperpendicular to said first and second electrodes, each third electrodecrossing a portion of each first and second electrode, each crossing ofa third electrode and a first electrode defining a counting cell, andeach crossing of a third electrode and a second electrode defining adisplay cell, said cover plate being spaced from each portion of eachthird electrode which is associated with a display cell to provide adisplay space in which gas glow can be viewed through said cover plate,there being a particle flow space extending from each counting cell toan adjacent display cell and to said display space associated therewith.2. The panel defined in claim 1 and including opaque areas obstructingviewing of said counting cells through said cover plate.
 3. The paneldefined in claim 1 wherein said cover plate has a top surface and abottom surface, and opaque areas are provided on said bottom surface ofsaid cover plate to shield selected ones of said cells from view throughsaid cover plate.
 4. The panel defined in claim 3 wherein said bottomsurface of said cover plate is provided with depressions which form saiddisplay spaces above each said third electrode.
 5. The panel defined inclaim 3 wherein said bottom surface of said cover plate has layers ofinsulating material secured to it to form each said display spacebetween them.
 6. The panel defined in claim 3 wherein said first plateis of an opaque insulating material to minimize light crosstalk betweensaid gas-filled cells when said cells glow.
 7. A display panel includinga gas-filled envelope consisting of a first insulating baseplate and asecond insulating cover viewing plate, means forming a plurality ofgas-filled cells in a commOn layer in said envelope, an anode electrodeand a glow cathode electrode associated with each cell, the anodeelectrode being positioned within said baseplate and said cathode beingpositioned in contact with said baseplate adjacent to said cover plate,each cathode being in operative relation with at least two of said cellsand with the anode electrodes therein, each such cathode including aslot providing gas communication between said two cells.
 8. The paneldefined in claim 7 and including means concealing at least one of saidcells from view so that, when said one cell glows, the glow cannot beseen but excited particles generated by the glow can flow through saidslot in said cathode to the other cell to prime said other cell forsubsequent firing.
 9. The panel defined in claim 8 wherein said coverplate is in contact with a portion of said cathode which overlays saidone cell and is spaced from the portion of said cathode which overlayssaid other cell, the space provided thereby being a glow display spacewhich presents unobstructed display to a viewer looking through saidcover plate.
 10. A display panel including a gas-filled envelopecomprising a first insulating baseplate and an insulating top coverviewing plate, said first base plate having a top surface and a bottomsurface with said top viewing plate sealed thereto in gastightengagement, said top plate having a top surface and a bottom surface, aplurality of parallel slots in said first plate, first electrodes seatedin said slots remote from said top surface of said first plate, secondelectrodes seated on said top surface of said first plate and orientedparallel to each other but at an angle to said first electrodes wherebyeach second electrode crosses each of said first electrodes and eachcrossing forms a gas-filled cell including a portion of a firstelectrode and a portion of a second electrode as the electrodes for thecell, said top plate being seated on portions of said second electrodes,said top plate being spaced from other portions of said secondelectrodes whereby a gas-filled display space is provided between saidother portions of said second electrodes and said cover plate, therebeing a gas communication path extending from each said first electrodethrough its said slot and between adjacent second electrodes into anadjacent slot and into the said gas-filled space above the portion ofsaid second electrode associated with said adjacent slot.
 11. The paneldefined in claim 10 and including means obstructing viewing of selectedones of said cells through said top plate.
 12. The panel defined inclaim 10 and including opaque areas provided on said bottom surface ofsaid top plate to shield selected ones of said cells from view throughsaid top plate.
 13. The panel defined in claim 12 wherein said bottomsurface of said top plate is provided with depressions which form saiddisplay spaces above each said second electrode.
 14. The panel definedin claim 12 wherein said bottom surface of said top plate has layers ofinsulating material secured to it to form each said display spacebetween them. there being a particle flow space extending from eachcounting cell to an adjacent display cell and to said display spaceassociated therewith.
 15. The panel defined in claim 1 and includingmeans concealing said counting cells from view so that, when each saidcounting cell glows, the glow cannot be seen by a viewer but excitedparticles generated by the glow can flow through said particle flowspace to adjacent display cells to prime said display cells forsubsequent firing.
 16. the panel defined in claim 1 wherein said thirdelectrode includes slots which extend from a counting cell to anadjacent display cell.
 17. The panel defined in claim 16 and includingmeans concealing said counting cells from view so that, when a countingcell glows, the glow cannot be seen by a viewer but excited particlesgenerated by the flow can flow through one of said slots in said thirdelectrode to an adjacent display cell to prime said display cell forsubsequent firing.
 18. The panel defined in claim 16 wherein said slotsextend along the entire length of each third electrode so that in effecteach third electrode comprises two narrow spaced-apart electrodeportions.
 19. The panel defined in claim 1 wherein each third electrodehas a bottom surface provided with depressions providing communicationpaths between adjacent first and second slots.
 20. The panel defined inclaim 1 wherein said third electrodes include apertures providing directcommunication between selected ones of said slots and the space abovesaid third electrodes.